Including fat-free yogurt in weight loss efforts may trim tummies faster
By Jennifer Warner
WebMD Weight Loss Clinic - Feature
Reviewed By Brunilda Nazario, MD
March 17, 2005 - Adding yogurt to your diet may rev up your body's fat-burning engines, speed weight loss, and trim your tummy, according to a new study.
Researchers found that obese adults who ate three servings of fat-free yogurt a day as part of a reduced-calorie diet lost 22% more weight and 61% more body fat than those who simply cut calories and didn't bone up on calcium. Yogurt eaters also lost 81% more fat in the stomach area than non-yogurt eaters.
"Not only did yogurt help the study participants lose more weight -- the average weight loss was 14 pounds -- they were about twice as effective at maintaining lean muscle mass," says researcher Michael Zemel, PhD, professor of nutrition at the University of Tennessee, in a news release. "This is a critical issue when dieting -- you want to lose fat, not muscle. Muscle helps burn calories, but it is often compromised during weight loss."
The results appear in the April issue of the International Journal of Obesity.
Researchers say the results add to a growing body of evidence that the calcium and protein derived from eating low-fat dairy products may help burn fat and promote weight loss.
In the study, researchers compared the effects of adding yogurt to a reduced-calorie diet on weight loss in 34 healthy obese adults who were divided into two groups.
For 12 weeks, the first group ate three 6-ounce servings of fat-free yogurt providing about 1,100 milligrams of calcium per day; the other group ate only one serving of dairy providing 400-500 milligrams of calcium per day. Both groups ate a controlled diet that contained 500 fewer calories than normal to stimulate weight loss.
As expected, all of the participants lost weight as a result of the calorie restriction. But the study showed that both weight and fat loss were significantly greater in the yogurt group.
For example, those on the low-calcium diet lost an average of 11 pounds, but those on the high-calcium yogurt diet lost an average of more than 14 pounds.
Participants on the yogurt diet also lost 81% more fat in the stomach area, which is the most dangerous type of fat. Excess fat in the midsection has been linked to an increased risk of heart disease, diabetes, stroke, and some forms of cancer.
In an editorial that accompanies the study, Ruth Harris, associate professor of foods and nutrition at the University of Georgia, says the results of the study are impressive and provide additional evidence for calcium and dairy protein playing a role in determining body weight and fat.
But she says researchers have yet to identify the scientific reasoning behind these proposed fat-burning effects.
"The possibility the increased levels of dietary calcium can reduce body weight or exaggerate weight loss is attracting an increasing amount of attention," writes Harris. "For many in the scientific community, however, it is difficult to embrace the efficacy of dietary calcium and dairy protein without a good understanding of the mechanisms responsible for the loss of body fat."
The study was supported by the Bell Institute of Health and Nutrition, General Mills Inc., which makes Yoplait.
SOURCES: Zemel, M. International Journal of Obesity, April 2005; vol 29: pp 391-397. News release, General Mills.
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